Device for blowing-in oxygen through the refractory lining of a metallurgical converter

ABSTRACT

In a tuyere assembly for blowing-in oxygen through the bottom of a metallurgical converter in which the tuyere comprises two tubes, a center tube passing oxygen into the converter and a tube surrounding the oxygen tube and opening into the converter, for conducting a protective fluid such as a liquid hydrocarbon into the converter, the improvement which consists principally in preventing hydrocarbon from forming an accumulation in the region adjacent to the outlet end of the dual tube tuyere, especially in the converter bottom adjacent thereto.

[ June 25, 1974 United States Patent [191 Courard et a].

III 266/35 4/1973 Saccomano et 266/41 [5 DEVICE FOR BLOWING-IN OXYGEN 86,304 1/1869 Holley 61 al. THROUGH THE REFRACTORY L N G O 3,330,645 7/1967 Moustier et A 12/1972 Knuppel 6t 3.1.

[75] Inventors: Camille Alphonse Courard,

Be,lgien'Angleur Belgium; Ernst Primary Examiner-Gerald A. Dost Rosenberg Germany Attorney, Agent, or Firm--Lawrence 1. Field Eisenwerk Gesellschaft [73] Assignee:

Maxmilianshutte GmbH, Sulzbach Rosenberg, Germany Dec. 8, 1972 In a tuyere assembly for blowing-in oxygen through the bottom of a metallurgical converter in which the tuyere comprises two tubes, a center tube [22] Filed:

ww mi oom fm m mnwpae .mt b gt S C e m m w p [21] Appl. No.: 313,309

gen into the converter and a tube surroundin 52 us. 266/41, 75/60 g tube Opening into the converter f0 51 rm. c216 5/48 mgapmtectwe [58 Field Of Seal'Ch........... 75/59, 60; 266/35, 36 P, the converter 3 lmpmvemem whlch 266/41 pally in preventing hydrocarbon from formin cumulation in the region adj [56] References Cited the dual tube tuyere, especially in the converter bot- UNITED STATES PATENTS adjacent therem' 51,399 Bessemer........................... 266/36 P 1 Claim, 5 Drawing Figures PATENTEBJUNZSIQM SHEET 2 OF 4 FATENTEB JUNZ 51974 SHEET 3 BF 4 PATENTEDmuzs ISM SHEET [1F 4 The present invention relates to a device for the insufflation of oxygen through the refractory lining, preferably through the bottom of a metallurgical converter. A related invention is described in U.S. Pat. application Ser. No. 313,382 filed concurrently with the present application by one of the present applicants.

It is known that refining of pig iron by means of pure oxygen blown in through the converter bottom has not been carried out, in particular on account of the corrosion affecting the refractory lining surrounding the tuyeres in the converter bottom.

Proposals have been advanced towards remedying this drawback, whereby tuyeres would be used which consist of two coaxial tubes, oxygen flowing through the inner tube and a gaseous or liquid protective medium, preferably one with endothermal reaction, flowing through the annular spacing between the two tubes. The results achieved when using such tuyeres have been of practical interest and better durability of the refractory lining surrounding these tuyeres was observed with the consequent increased durability of converter bottoms so equipped.

Using such dual concentric tubes tuyeres, however, does entail certain difficulties, mostly on account of the difficulty in properly positioning the tubes relative to each other when these tubes are emplaced and because of the tube dimensions required to meet the conditions of pressure and rates of the fluids introduced into the converter, particularly when the protective fluid is a liquid hydrocarbon.

. In the course of refining operations performed with dual, coaxial tubes tuyeres and blowing through the converter bottom, in which oxygen was passed through the inner tube and a liquid hydrocarbon was passed through the outer one, it was found that a definite amount of hydrocarbon would remain unconsumed. This residual amount tends to deposit around the tuyeres and to increasingly impregnate the porous, refractory material forming the converter bottom, until it reaches the bottom plate and finally spreads out on the work-floor.

In order to remedy such drawbacks and the danger associated with it, attempts have been undertaken to regulate the rate of injection and the pressures of the oxygen and of the protective fluid and also to reduce the size of the annular space provided for hydrocarbon flow. However, it has not been possible to prevent penetration and leakage of the liquid, non-burned hydrocarbon. 1

The principal object of the present invention is to provide a blowing-in device with a dual, coaxial tubes tuyere constructed and operated so as to prevent the outflow of the introduced but non-burned hydrocarbon from the converter bottom.

The present invention will be explained in greater detail from a consideration of the embodiments shown in the drawings in which:

FIG. 1 is an axial, longitudinal section through a blowing in device according to the invention;

FIG. 2 is a view similar to FIG. 1 showing such a device provided with a tuyere extension;

FIG. 3 is a section through the extension of FIG. 2;

FIG. 4 is a top view of the extension of FIGS. 2 and 3; and

FIG. 5 is an axial longitudinal section through another embodiment of the invention.

In the device shown in FIG. 11, a tubular space extends along the entire length 2 of the dual, coaxial tubes tuyeres which is inserted into refractory mass 3 forming the converter bottom. Within space 1 there is provided an annular, hollow base 4 which is welded to the converter wall or bottom plate 5, and also a sleeve 6 fastened on annular base 4, said sleeve 6 being filled with a tamped refractory material 7. The wall of annular base 4 makes contact with sleeve 6 and with the wall of bottom plate 5, both base 4 and bottom 5 being provided respectively with at least one orifice 8 and one pressure duct 9 arranged in suchmanner that the space 1 may be put under a definite pressure in order to prevent downward hydrocarbon outflow through the refractory substance 7 contained in sleeve 6.

Preferably the axis of space 1 coincides with that of tuyere 2.

According to the invention, the sleeve 6 advantageously consists of metal preferably of steel, with a thickness of about 1 mm. This small thickness is advantageous so that no infiltration path into the refractory mass of the converter bottom is available in case of the metal melting.

The outer diameter of the sleeve is preferably from three to six times the outer diameter of the tuyere outer tube.

Also according to the invention, a suitable refractory material 7 filling the space between sleeve 6 and tuyere 2 outer tube is the same as that forming the converter bottom 3.

In case the protective medium blownthrough the tuyere outer tube is a liquid hydrocarbon, practice has shown that the clearance between the two tuyere tubes must be fairly small while still sufficient to allow the desired flow rate. It has been found according to the invention that the annular space between the two coaxial tubes is preferably such as to allow inserting the inner tube in the outer one against only slight friction.

In order to achieve the desired hydrocarbon injection rates, the dual tuyere advantageously are constructed as follows:

1. either the outside of the inner tube and/or the inside of the outer tube are provided with longitudinal or helical grooves, or I 2. the outside of the inner tube is provided with several evenly distributed zones on which occurs the slight friction with the outer tube, these zones being separated by rectilinear, flattened areas.

After refining a certain number of charges in a converter, the bottom of which is equipped with dual ,tuyeres, some of these must be repairedor replaced. Generally it is enough to replace the inner tube, and mounting of these tuyeres on the bottom plate is such that the inner tube may be easily withdrawn and replaced with another. But when the spacing between the coaxial tubes is equal to a space allowing inserting the inner tube into the outer one against only light friction, experience shows that at high temperatures, withdrawal of the inner tube is virtually impossible because of temperature expansion making a single entity of the two tubes.

In such a case, the construction shown in FIGS. 2, 3 and 4 for the insufflation device is provided with the following:

A tuyere support secured on the inner surface 11 of bottom plate 5 of the converter, at the position at which the tuyere is inserted; an annular flange 12 fastened to the terminal fitting 13 from the feed lines for the media to be blown in; and at least four pressurescrews 14 projecting beyond threaded supports 15 in annular flange l2 and abutting tuyere support 10 in such manner that the latter will contribute a definite pressure when the screws act upon the tuyere for the purpose of withdrawing the two coaxial tubes together.

in the vicinity of the bottom plate 5. In this case there are no orifices 8 and no pressure ducts 9 as in the illustrative embodiment of FIG. 1, and the sleeves inside will be free from pressure. The weld-connection 19 between conical part 18 and outer tube 2 prevents the protective medium from flowing out from the converter bottom.

We claim:

1. A device for blowing in oxygen through the refractory lining of a metallurgical convertor comprising:

a bottom plate;

a refractory lining supported on said plate;

a dual, coaxial tubes tuyere, including an inner tube for blowing in oxygen and an outer tube for blowing in protective fluid, said tubes extending through said lining and said bottom plate;

a space located in said lining which along its entire height surrounds that part of the tuyere which extends through the refractory lining and which is sealed at its bottom, so as to be hermetic with respect to gases and liquids, by means of a sleeve coaxial with said tuyere and provided with a conical part which is welded at its tip to said tuyere outer tube. 

1. A device for blowing in oxygen through the refractory lining of a metallurgical convertor comprising: a bottom plate; a refractory lining supported on said plate; a dual, coaxial tubes tuyere, including an inner tube for blowing in oxygen and an outer tube for blowing in protective fluid, said tubes extending through said lining and said bottom plate; a space located in said lining which along its entire height surrounds that part of the tuyere which extends through the refractory lining and which is sealed at its bottom, so as to be hermetic with respect to gases and liquids, by means of a sleeve coaxial with said tuyere and provided with a conical part which is welded at its tip to said tuyere outer tube. 